27 September 2010

"Artificial leaf" generates electricity

by Kate Melville

Solar cells that mimic nature have been created at North Carolina State University where water-gel-based artificial leaves containing chlorophyll produce electricity. Lead researcher Orlin Velev says the "natural" solar cells have the potential to be less expensive and more environmentally friendly than current silicon-based solar cells.

The bendable devices are composed of water-based gel infused with light-sensitive molecules coupled with electrodes coated in carbon nanotubes or graphite. The light-sensitive molecules get "excited" by the sun's rays to produce electricity, similar to plant molecules that get excited to synthesize sugars in order to grow, explains Velev, whose work has been published in the Journal of Materials Chemistry.

The successful demonstration now means the researchers will work to fine-tune the water-based photovoltaic devices, making them even more like real leaves. "The next step is to mimic the self-regenerating mechanisms found in plants," Velev says. "The other challenge is to change the water-based gel and light-sensitive molecules to improve the efficiency of the solar cells."

The research team hopes to mimic how nature harnesses solar energy by avoiding the use of synthetic light-sensitive molecules and concentrating instead on naturally derived products - like chlorophyll - which are easily integrated into the water-gel matrix devices.

Velev imagines a future where home roofs could be covered with soft sheets of electricity-generating artificial-leaf solar cells but is cautious about overpromising. "The devices are still of relatively low efficiency and there is a long way to go before this can become a practical technology," Velev says. "However, we believe that the concept of biologically inspired soft devices for generating electricity may in the future provide an alternative [to] present technologies."